Revert "Revert "luna: add support for .BMP resources""

This reverts commit e4fb0a691ab62015f49c4cb42503d16f59a98d68.
re-add escape_xml_chars() lost by c5151bb8edf5f2c4663f3435239ed87548f2b369
Add nspire-tools path command

-Returns absolute path to the ndless sdk
Fix Makefile.tpl

-$(DESTDIR) used together with vpath
Newer version of nspireio
Add support for --gc-sections
Fix SCREEN_BASE_ADDRESS for C++